How does the air get in non-bladder tanks?

I have a problem keeping air in my non-bladder tank and have to constantly drain it to put air back in. Adding to the problem is my AC is a water to air heat pump so the water is on quite a bit and quite often.

I realize a large air bladder tank is optimal but my finances can't afford it.

Specs: 1.75 HP deep well pump 375' deep with a large non-bladder air tank.

No leaks air or water show up anywhere.

I thought that the surge of the pump coming on somehow added air to the tank a little each time but obviously this is not working so a complete draining and refill only lasts about a 2 weeks or so and it's water logged again.

I'm not sure I understand. YOu have a storage tank that you expect to hold air and water with no bladder separating them? Usually, the storage tank has a bladder to keep the system pressurized while the pump is off. Any tank that has air and water in it will eventually disolve all of the air into the water, and you'll only have a tank full of water. If the water doesn't "disappear", it would typically bubble out when you run the water through the opened faucet.

Does this tank have an air valve on it? If it does and you open it while it exhibits the problem you indicate, does water come out of it? If so, then you need a new tank.

With the pump off, a valve opened in the house to relieve the pressure, the tank should measure a couple of pounds less than the turn on setting of your pump. You should be able to use a (quality - hopefully accurate) tire pressure guage to check this.

In the "old days" before bladder tanks the system was designed so that the piping between the pump and the tank drained down and filled with air between cycles. Then that air entered the tank. A "snifter" valve was installed on the tank to release excess air so the tank did not fill with air and keep the water out. In your case, unless you have a means to unplug an opening near the top of the tank you may not be draining the tank completely so it is not starting with a full tank of air, which will be compressed to about 1/2 its original volume depending on the system's pressure. It is possible to fill the tank with air using an air compressor, but the process is somewhat difficult to describe although it is fairly easy to do, since you have to exhaust water, up to a point, as the air is inserted but then stop draining the water as soon as the level reaches the bottom of the tank and then continue pumping air in until it reaches the 4 psi less than the pump turn on point, and then put everything back to normal.

Well, HJC, I learned something (not uncommon!). Seems like that system would be problematic (course a bladder tank fails occassionally, too). It would seem that you still would periodically need to pump some air in - some would continually be disolving into the water (sort of like carbonation).

In the "old days" before bladder tanks the system was designed so that the piping between the pump and the tank drained down and filled with air between cycles. Then that air entered the tank. A "snifter" valve was installed on the tank to release excess air so the tank did not fill with air and keep the water out.

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Thanks for the reply.

I do fill the tank up with air a compressor because it's easier and quicker. I turn off the pump, and open the lowest valve then add air until it comes out the low end of the hose. If anything I'm over filling it but that doesn't last long because the "snifter" lets it out almost immediately after turning the pump back on.

You mentioned "that the piping between the pump and than drained down and filled with air between cycles" but the way it was explained to me by the well man was the pressure boost when the pump started caused "something" to pump a little air into the tank and that "snifter valve" keeps it from overfilling.

With the backflow valve down near the pump in the bottom of the well I don't see how water could "drain down" and fill with air unless it sucks "some" air in that little air pressure valve (like on a tire).

But maybe that's the culprit, the valve spring is too strong and not opening on suction. It's a cheap thing to replace anyway so maybe I'll try it.

These non-bladder tanks are common in this area because contractors can save a few bucks and they do work without much trouble as thousands have them. At other places I lived I never had to drain the tank except maybe once per year. I'm having to do it every two weeks here because the pump is coming on all the time with the AC system.

First, if you are pumping air into the tank remove the snifter so the air stays in, then pump a "smidgen" of water into the tank and then continue pumping air in until the tank is pressurized to the normal 4 psi below the pump start point. That will approximate a bladder tank, although you will have to repeat the process at some time in the future, just not as often as you do now.

I am going to encourage you to go buy a large (as large as you can afford and have room for) bladder tank and install it. You have a deep pump that would cost alot to replace. The less the pump kicks on, the longer it will last. In my mind, there is no contest.
These tanks are actually very problematic (they do not actually work well at all).
Deb
The Pipewench

I was hoping I could fix this for a year (cheapley) until I can save up the money. Those large bladder tanks like I need are very expensive for a retired person with low income. Too bad I didn't notice it when they were building the house and it could have added cheaply.

Adding air every 2 weeks is what I'll have to do for now and it can't be overfilled with a faucet open because it opens the relief valve that is supposed to keep it from having too much air.